The amount of data stored on a storage system, plus the amount of unused formatted capacity in that system.

There is no way to precisely predict the effective capacity of an unloaded system. This measure is normally used on systems employing space optimization technologies.

An estimated calculation may be made as follows. Let D = the size of data already stored, Fd be the formatted capacity used to store that data, and Ft be the total formatted capacity on the system. Then the estimated effective capacity Ee is given by the formula Ee = D / (Fd / Ft). No unused formatted capacity is used in the estimation calculation.

The efficiency of any electrical device which transforms one type of power into another.

Efficiency is defined as output power divided by input power expressed as a percentage. All electrical components in a computer system, such as PDUs, UPSs and power supplies, incur some degree of power loss. Determining the total power loss in smaller systems with one power supply can be done by straightforward measurement of wall plug power and the total power supplied at the power supply's outputs. Larger systems require more complex methods.

Data or information of any kind and from any source, whose temporal existence is evidenced by being stored in, or on, any electronic medium. [ISO/IEC 27040]

Electronically Stored Information (ESI) includes traditional e-mail, memos, letters, spreadsheets, databases, office documents, presentations, and other electronic formats commonly found on a computer. ESI also includes system, application, and file-associated metadata (3.26) such as timestamps, revision history, file type, etc. Electronic medium can take the form of, but is not limited to, storage devices and storage elements.

Defines a uniform taxonomy of storage subsystems and a standard way of measuring power efficiency of the storage subsystems defined in the taxonomy. For more detailed information, please consult the SNIA Emerald Program website (https://www.snia.org/emerald).

While power and energy efficiency look about the same to a layman, the numbers may be different (even neglecting the units) on account of temporal variations in supply voltages, power and load factors and so on.

Software that manages all aspects of an organization's assets, systems, services and functions.

ERM systems manage a set of resources in the wider perspective of an organization's entire business. Managing in an enterprise context requires that entities be named uniquely and locatable within the enterprise, that heterogeneity of platforms and services may be assumed, and that the dynamic nature of the environment is taken into account.

A measure of the amount of uncertainty that an attacker faces to determine the value of a secret. [NIST SP 800-63]

The value is sometimes measured in bits of security strength, where a value of 0 indicates no security strength (i.e., full predictability or no randomness) and a positive value indicates increasing security strength.

A forward error correction technology used to provide data resiliency and long-term data integrity, by spreading data blocks and parity information across multiple storage devices or systems that may be in multiple physical locations.

Both the level of resiliency and where erasure coding is applied (at the array, at the node, or at the system level) can significantly affect how much processing overhead it consumes.

A scheme for checking the correctness of data that has been stored and retrieved, and correcting it if necessary.

An ECC consists of a number of bits computed as a function of the data to be protected, and appended to the data. When the data and ECC are read, the function is recomputed, the result is compared to the ECC appended to the data, and correction is performed if necessary. Error correcting codes differ from cyclic redundancy checks in that the latter can detect errors, but are not generally capable of correcting them. See cyclic redundancy check.

The SNIA uses the base 10 convention commonly found in I/O-related and scientific literature rather than the base 2 convention (1,152,921,504,606,846,976, i.e., 260) common in computer system and software literature.

The SNIA uses the base 10 convention commonly found in I/O-related and scientific literature rather than the base 2 convention (1,152,921,504,606,846,976, i.e., 260) common in computer system and software literature.

A set of one or more non-concurrent related sequences passing between a pair of Fibre Channel ports.

An exchange encapsulates a "conversation" such as a SCSI task or an IP exchange. Exchanges may be bidirectional and may be short or long lived. The parties to an exchange are identified by an Originator Exchange-Identifier (OX-ID) and a Responder Exchange_Identifier (RX_ID).

A single disk may be organized into multiple extents of different sizes, and may have multiple (possibly) non-adjacent extents that are part of the same virtual disk-to-member disk array mapping. This type of extent is sometimes called a logical disk.

A diagram used to specify optical or electrical signal transition characteristics for transmitters, in which the horizontal axis represents normalized time from pulse start and the vertical axis represents normalized amplitude.